2. (Increment and Decrement Operator) Write a C# program that accepts the values of two variables (the type double and named as v1 and v2) from a ser. Then, the program will perform the following operations and output the result of each operation: (20 points) V1++ ++v1; V1-v2++ v1 +V2; v1 /=v2; 3. (Diameter, Circumference and Area of a Circle) In this chapter, you have learned about integers and the type int. C# can also represent floating-point numbers that contain decimal points, such as 3.1415926. Write a C# program that accepts the value of a variable (the type int and representing the radius of a circle), then calculates the circle's diameter, circumference and area, and outputs the values of the circle's diameter, circumference and area. When writing the program, the formulas need are listed below: (r is the radius) diameter2r